Stud welding apparatus and process

Abstract

A part of hard, weldable material which has been through drilled and tapped is sealed by stud welding a stud thereover to form a fluid-tight article which is used to facilitate the connecting of other parts. The threads are protected during stud welding by a conductive refractory insert in the tapped through bore thereby preventing molten metal or the like from entering the same. A magnetic jig serves to hold the insert and as an electrical connector of the insert to the part to permit the proper arc to be drawn during stud welding.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. Apparatus for facilitating the drawn arc stud welding closure of hole ends in metal objects, comprising a stud larger than and for stud welding over a hole end in a metal object, an electrically conductive refractory insert for drawing a welding arc removably secured within said hole with an end of the insert approximately flush with said hole end, a flux projection secured to the end of a stud to be stud welded against the metal object, and connecting means for electrically connecting the insert to the metal object, whereby stud welding equipment may be electrically connected to the insert and stud for drawing a welding arc between them and effecting the stud welding closure. 
     
     
       2. Apparatus as set forth in claim 1 wherein said connecting means include securing means for removably securing said insert within said hole and approximately flush with the end of the hole. 
     
     
       3. Apparatus as set forth in claim 2 wherein said connecting means comprise a jig with magnetic mounting means, which jig is operative from a magnetically attached position on the side of said metal object opposite said stud. 
     
     
       4. Apparatus as set forth in claim 3 wherein said jig includes clamp means for making said insert immovable. 
     
     
       5. Apparatus as set forth in claim 4 wherein said clamp means includes means for providing electrical connection between the jig and insert. 
     
     
       6. Apparatus as set forth in claim 5 wherein said magnetic mounting means comprise a permanent magnet, and wherein said jig has a passageway therethrough for accomodating the insert. 
     
     
       7. Apparatus as set forth in claim 6 wherein said insert is in the form of a graphite rod penetrating said passageway. 
     
     
       8. A jig for use in the drawn arc stud welding closure of the ends of holes in metal objects comprising means for removably securing within a hole in a metal object an electrode means for drawing a welding arc with an end of the electrode means approximately flush with said hole end, conductive means for electrically connecting the electrode means with said metal object, and mounting means for securing the jig to the metal object, said electrode means comprising an electrically conductive refractory insert. 
     
     
       9. A jig as set forth in claim 8 wherein said mounting means comprise an electrically conductive permanent magnet. 
     
     
       10. A jig as set forth in claim 9 wherein said magnet has electrically conductively secured to one end an electrically conductive plate means, with a passageway through said plate means and magnet for accomodating said electrode means, and wherein the plate means include clamp means for adjustably engaging the electrode means and for providing good electrical connection between the plate and electrode means, said conductive means comprising said magnet, plate means and clamp means. 
     
     
       11. A jig as set forth in claim 10 wherein said magnet is comprised for metal and said plate means comprise a softer more easily drilled and tapped metal than the metal of which the magnet is comprised. 
     
     
       12. A jig as set forth in claim 11 wherein said clamp means comprise a threaded shaft and clamp screw. 
     
     
       13. A method of closing hole ends in metal objects comprising the steps of: removably securing within a hole in a metal object a refractory electrode means for drawing a welding arc with an end of the electrode means approximately flush with said hole end, connecting stud welding apparatus to the electrode means and a stud, and stud welding the stud to the metal object during which a welding arc is struck between the stud and electrode means.   
     
     
       14. A method as set forth in claim 13 wherein the welding arc is initially struck between said electrode means and a flux projection secured to the stud end to be welded. 
     
     
       15. A method as set forth in claim 14 wherein a good electrical connection is provided said electrode means and said metal object. 
     
     
       16. A method as set forth in claim 15 including the step of electrically connecting a stud welding power supply to said electrode means by connecting the power supply to said metal object. 
     
     
       17. A method as set forth in claim 16 wherein said good electrical connection between the electrode means and said metal object is provided by means of a magnetic jig.